21828861 has 6 divisors (see below), whose sum is σ = 31530590. Its totient is φ = 14552568.

The previous prime is 21828847. The next prime is 21828869. The reversal of 21828861 is 16882812.

It can be written as a sum of positive squares in only one way, i.e., 16040025 + 5788836 = 4005^2 + 2406^2 .

It is not a de Polignac number, because 21828861 - 2⁷ = 21828733 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21828869) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1212706 + ... + 1212723.

Almost surely, 2^21828861 is an apocalyptic number.

It is an amenable number.

21828861 is a deficient number, since it is larger than the sum of its proper divisors (9701729).

21828861 is a wasteful number, since it uses less digits than its factorization.

21828861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2425435 (or 2425432 counting only the distinct ones).

The product of its digits is 12288, while the sum is 36.

The square root of 21828861 is about 4672.1366632409. The cubic root of 21828861 is about 279.4754678221.

The spelling of 21828861 in words is "twenty-one million, eight hundred twenty-eight thousand, eight hundred sixty-one".